Neurogenetics of lead toxicity in Drosophila

描述（由申请人提供）：重金属毒性是一个世界性的健康问题。铅暴露尤其令人关切，因为低浓度对儿童的认知发育有不利影响。虽然铅的神经毒性机制已经得到了很好的研究，但缺乏关于人类群体中铅暴露影响的遗传易感性的信息，以及旨在确定可能加剧或改善暴露风险的等位基因的研究。这种信息很难获得，特别是在儿童中，因为很难量化接触的开始、持续时间和程度，很难衡量铅接触在发育后期变得明显的不利影响，很难评估同时接触多种、往往是未知的环境毒素的影响，也很难在说明人口结构的同时获得足够的人口样本。这些问题可以通过在模型系统中鉴定具有人类直系同源物的候选风险等位基因来规避，其随后可以应用于对人类群体的转化研究。黑腹果蝇是一个有利的模型，因为遗传背景和环境，包括铅暴露，都可以精确控制。本R21提案是一项探索性可行性研究，旨在为后续R 01应用奠定基础， 果蝇遗传学的全部力量，以获得对铅暴露易感性的遗传基础的见解。为了确定与铅暴露敏感性相关的等位基因，我们将利用来自罗利种群的野生近交系种群（具有完全测序的基因组（黑腹果蝇遗传参考小组，DGRP）），并利用DGRP小组内广泛的自然变异进行全基因组关联研究（GWAS）。本申请的具体目的是：（1）在205个具有完全测序的基因组的近交野生衍生系中鉴定与铅暴露对发育时间、存活力和运动活性的影响相关的常见DNA序列变体;以及（2）使用大规模平行批量DNA测序作为一种补充方法，以确定与铅暴露效应相关的常见和罕见等位基因，这些等位基因在一个由极端敏感和抗性品系衍生的高级互交群体。我们将测量发育时间，生存能力和运动活动的DGRP线饲养和不暴露于醋酸铅，并确定单核苷酸多态性（SNP）与铅敏感性的变化。随后的R 01奖将重点关注候选等位基因的更详细的验证和表征，它们之间的上位相互作用，以及遗传网络和神经回路之间的联系，这些联系决定了对铅神经毒性的敏感性。这些实验的结果将与人类环境健康高度相关。

DESCRIPTION (provided by applicant): Heavy metal toxicity is a world-wide health problem. Lead exposure, especially, is of concern due to the adverse effects of low concentrations on cognitive development in children. Whereas neurotoxic mechanisms of lead have been well studied, information regarding genetic susceptibility to the effects of lead exposure in human populations and studies aimed at identifying alleles that may exacerbate or ameliorate exposure risk are lacking. Such information is difficult to obtain, especially in children, because it is dificult to quantify the onset, duration and extent of exposure, measure adverse effects of lead exposure that become manifest at a later stage of development, assess the effects of simultaneous exposure to multiple, often unknown, environmental toxins, and obtain adequate population sample sizes while accounting for population structure. These problems can be circumvented by identifying candidate risk alleles with human orthologues in model systems, which can subsequently be applied in translational studies to human populations. Drosophila melanogaster presents an advantageous model, since both the genetic background and environment, including exposure to lead, can be controlled precisely. This R21 proposal is an exploratory feasibility study to lay the foundation for a subsequent R01 application to exploit the full power of Drosophila genetics to gain insights in the genetic underpinnings of susceptibility t lead exposure. To identify alleles associated with sensitivity to lead exposure, we will take advantage of a population of wild-derived inbred lines from a Raleigh population with fully sequenced genomes (the Drosophila melanogaster Genetic Reference Panel, DGRP) and capitalize on extensive natural variation within the DGRP panel to conduct a genome-wide association study (GWAS). The Specific Aims of this application are: (1) To identify common DNA sequence variants associated with the effects of lead exposure on development time, viability and locomotor activity in 205 inbred wild- derived lines with fully sequenced genomes; and (2) To use massively parallel bulk DNA sequencing as a complementary approach to identify both common and rare alleles associated with effects of lead exposure that segregate in an advanced intercross population derived from extreme sensitive and resistant lines. We will measure development time, viability and locomotor activity in the DGRP lines reared with and without exposure to lead acetate, and identify single nucleotide polymorphisms (SNPs) associated with variation in sensitivity to lead. A subsequent R01 award will focus on a more detailed validation and characterization of candidate alleles, epistatic interactions among them, and the link between genetic networks and neural circuitry that determine sensitivity to lead neurotoxicity. Results from these experiments will be highly relevant to human environmental health.